Hi can someone me with this that would be great and if you could explain that would be even better ( especially for #5) ( the one i need the most in is 6 and 5)

No.5 the surface area =the area of each face that mean there is 6 faces of a rectangular so the area = 2*(3*5)+2*(3*7)+2*(5*7) = 142 cm^2
no .6 the surface area of cube = 6*L^2 ,, where L is length of cube so
6*L^2 = 150 and by solving this equation we get L= 5 in.