SOLUTION: Hi jack and jill had some money in the ratio of 5:2. They jointly paid for a restaurant bill respectively in the ratio of 2:1. If jill spent 20 percent of her money and jack had

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Question 1147256: Hi
jack and jill had some money in the ratio of 5:2. They jointly paid for a restaurant bill respectively in the ratio of 2:1. If jill spent 20 percent of her money and jack had 126 dollars left, how much was the bill.
thanks

Found 2 solutions by josmiceli, MathTherapy:
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +a+ = amount of Jack's money
Let +b+ = amount of Jill's money
--------------------------------------------
+a%2Fb+=+5%2F2+
+a+=+%285%2F2%29%2Ab+
+%28+a+-+126+%29+%2F+.2b+=+2%2F1+
------------------------------------
by substitution:
+.2b+%2F+%28+%285%2F2%29%2Ab+-+126+%29+=+2+
+.2b+=+5b+-+252+
+4.8b+=+252+
+b+=+52.5%0D%0Aand%0D%0A%7B%7B%7B+a+=+2.5%2A52.5+
+a+=+131.25+
-----------------------
+.2b+=+.2%2A52.5+
+.2b+=+10.5+
and
+a+-+126+=+131.25+-+126+
+a+-+126+=+5.25+
-------------------------------
+10.5+%2B+5.25+=+15.75+
The bill was $15.75
-------------------------------
check:
+a%2Fb+=+5%2F2+
+131.25+%2F+52.5+=+2.5+
+2.5+=+2.5+
OK
check the math & get a 2nd opinion if needed



Answer by MathTherapy(10555) About Me  (Show Source):
You can put this solution on YOUR website!
Hi
jack and jill had some money in the ratio of 5:2. They jointly paid for a restaurant bill respectively in the ratio of 2:1. If jill spent 20 percent of her money and jack had 126 dollars left, how much was the bill.
thanks
With Jack to Jill's ratio being 5:2, and with the multiplicative factor being x, we can say that the original amounts Jack and Jill had were: 5x and 2x
With a 2:1 bill-ratio, and b being the amount of the bill, Jack paid matrix%281%2C5%2C+2%2F3%2C+of%2C+%22b%2C%22%2C+or%2C+2b%2F3%29
After paying his portion of bill, Jack had 5x++-++2b%2F3 left, which was $126
So, we get: matrix%281%2C3%2C+5x++-++2b%2F3%2C+%22=%22%2C+126+%29
15x - 2b = 378 ------ Multiplying by LCD, 3 ------- eq (i)

With a 2:1 bill-ratio, and b being the amount of the bill, Jill paid matrix%281%2C5%2C+1%2F3%2C+of%2C+%22b%2C%22%2C+or%2C+b%2F3%29
After paying her portion of bill, Jill had .8(2x) left
So, we get:
6x - b = 4.8x ------ Multiplying by LCD, 3
6x - 4.8x - b = 0
1.2x - b = 0 --------- eq (ii)
- 2.4x + 2b = 0 ------ Multiplying eq (ii) by - 2 ------- eq (iii)
12.6x = 378 ---------- Adding eqs (iii) & (i)
matrix%281%2C5%2C+x%2C+%22=%22%2C+378%2F12.6%2C+%22=%22%2C+30%29

1.2(30) - b = 0 --- Substituting 30 for x in eq (ii)
36 - b = 0
36 = 0 + b
b, or highlight_green%28matrix%281%2C3%2C+bill%2C+%22was%3A%22%2C+%22%2436%22%29%29