Question 1169281
Three friends A, B and C dine out and decide to split the bill according to what they order.
 A’s portion and B’s portion of the bill totaled $35,
a + b = 35
 while B’s portion of the bill was $5 less than C’s portion of the bill.
b = c - 5
 The ratio of A’s portion to C’s portion of the bill is 4:5.
{{{a/c}}} = {{{4/5}}}
cross multiply
5a = 4c
a = {{{4/5}}}c
a = .8c
;
In the first equation, replace a with .8c and b with (c-5)
.8c + (c-5) = 35
1.8c = 35 + 5
1.8c = 40
c = 40/1.8
c = $22.22
:

 Determine the total bill amount.
add to a + b = 35
35 + 22.22 = $57.22 is the total bill