Question 187633
I can!...but first, since you wrote "5y=10x=20" did you really mean to write:
{{{5y = 10x+20}}} or
{{{highlight(5y+10x = 20)}}} ???
I suspect the latter is what you meant so I'll use that, but if I'm wrong, please resubmit with the appropriate correction.
Solve:
1) {{{y = -4x+3}}}
2) {{{5y+10x = 20}}}
Substitute equation 1) for y into equation 2) to get:
2a) {{{5(-4x+3)+10x = 20}}} Simplify and solve for x.
2a) {{{-20x+15+10x = 20}}}
2a) {{{-10x+15 = 20}}}
2a) {{{-10x = 5}}}
2a) {{{highlight(x = -1/2)}}} Now substitute this value of x into equation 1) and find y.
1) {{{y = -4x+3}}} Substitute {{{x = -1/2}}}
1) {{{y = -4(-1/2)+3}}} Evaluate the right side.
1) {{{y = 2+3}}}
1) {{{highlight(y = 5)}}}
The solution: (-1/2, 5)