In evaluating a double integral over a region D, a

In evaluating a double integral over a region D, a sum of iterated integrals was obtained as follows: 

∬Df(x,y)dA=∫20∫4y0f(x,y)dxdy+∫102∫10−y0f(x,y)dxdy.

Sketch the region D and express the double integral as an iterated integral with reversed order of integration. 

∫ba∫g2(x)g1(x)f(x,y)dydx 

a=  b=  

g1(x)=  g2(x)=