<PRE><B>Question 1062128</B>
10 gm sweets are x
5 gm sweets are 2x
10x+5(2x)=120
20x=120
x=6
2x=12
He has 18 sweets, 6 of them 10 gm and 12 of them 5 gm. They add up to 120 gm.
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 (1/x)+(1/y)=7/10
 (3/x)-(5/y)=1/2
Multiply everything by 10xy to clear fractions for the first and 2 xy for the second
10y+10x=7xy
6y-10x=xy
add them
16y=8xy
divide by y
16=8x
x=2
substitute into first
(1/2)+(1/y)=7/10
(1/y)=2/10=1/5y
y=5
Check in the second
3/2-5/5=1/2, and 1.5-1=0.5
(2,5)</PRE>