5:65h
6:110x
7:12x
I hope this helps
For each equation give X a value and solve for Y, do this at least two times for each equation.
Plot those dots on a graph to draw two lines.
The solution is where the two lines cross.
You will see the lines cross at (-1,-2)
Let x = small number
y=large numebr
x+y = 90
y-4x=15
substitute
we get:
x=21
y=90-21 = 69