Question

Y = 0.8x+ 7.2
20x + 32y = 48

Answer 1

x=-4, Y=4

Explanation:

20x+32(0.8x+7.2)=48

45.6x =48-230.4

x=-4

substitute x=-4 in y eqn

y=-3.2+7.2

y=4

Answer 2

Explanation:

y = 0.8x+ 7.2 ..........(1)

20x + 32y = 48 .........(2)

Substitute (1) in (2)

20x +32*(0.8x+7.2) = 48 expand

20x + 25.6x+230.4 = 48 add

45.6x+230.4 = 48 transpose and simplify

45.6x = 48-230.4 = -182.4

x = -182.4 / 45.6

x = -4