Question

Solve equation using substitution
x/3+y/5=7
x+y=27

Answer 1

y=27-x

replacing in the other equation:

x/3 + (27-x)/5 =7
x/3 + 27/5 - x/5 =7
(5x-3x)/15 + 27/5 = 7
2x/15 + 27/5 = 7
2x/15 = 7 - 27/5
2x/15 = (35-27)/5
2x/15 = 8/5
2x = (15*8)/5
2x=24
x=12

then

y = 27-x
y=27-12
y=15