## Calculus with Applications (10th Edition)

By Funibi's Theorem $\int^{b}_{a}\int^{d}_{c}f(x,y)dydx=\int^{d}_{c}\int^{b}_{c}f(x,y)dxdy$ so $\int^{4}_{2}\int^{5}_{1}(3x+4y)dy dx=\int^{5}_{1}\int^{4}_{2}(3x+4y)dxdy$