To solve the system of equations, we can use the method of substitution. We can solve one equation for one variable and substitute it into the other equation.
From the first equation, we can solve for x:
3x - 4y = 40
3x = 4y + 40
x = (4y + 40)/3
Substituting x into the second equation:
5((4y + 40)/3) - 5y = 55
(20y + 200)/3 - 5y = 55
20y + 200 - 15y = 165
5y = -35
y = -7
Substituting y back into x = (4y + 40)/3:
x = (4(-7) + 40)/3
x = ( -28 + 40)/3
x = 12/3
x = 4
Therefore, the solution to the system of equations is (4, -7).