To calculate the area of a rectangle you multiply the length of the the sides, on 38) the sides are 4 and (3x-2) so to find the area do 4 x (3x-2) = 12x-8
To find the area of a right angled triangle you multiply the two sides and then divide by two, so for 39) and 40) follow this method but divide by two after as they’re triangles to find the area for these
