To solve this system of equations, we can use the method of substitution or elimination. Let's use the substitution method.

From the second equation, we can express x in terms of y:
x = 7 + 3y

Now substitute x in the first equation:
5(7 + 3y + 2y) - 3(7 + 3y - y) = 99
35 + 25y - 21 - 9y = 99
4y + 14 = 99
4y = 85
y = 21.25

Now substitute y back into the expression for x:
x = 7 + 3(21.25)
x = 7 + 63.75
x = 70.75

Therefore, the solution to the system of equations is x = 70.75 and y = 21.25.