Question

Use substitution to solve each of the following pairs of simultaneous equations for x and y in terms of a and b:
a) ax + y = b
y = bx
b) ax + by = b
x = by

Answer 1

I'll do (a). #b is done the same way.
since y = bx, we substitute that into
ax + y = b
and we then have
ax + bx = b
(a+b)x = b
x = b/(a+b)
Then, since y = bx,
y = b * b/(a+b) = b^2/(a+b)