Solve the linear simultaneous equations: 3x + 5y = 45, 2x - 9y = -7

x = 10, y = 3. From the second equation, we have x = (9y - 7)/2. Substituting this expression for x into the first equation gives 3(9y - 7)/2 + 5y = 45. 3(9y - 7) + 10y = 90. 27y - 21 + 10y = 90. 37y = 111. y = 111/37 = 3. Finally, substituting our result for y into our expression for x gives x = (27 - 7)/2 = 20/2 = 10