Question 295431
H=B+3
A=BH/2
35=B(B+3)/2
35=(B^2+3B)/2
B^2+3B=35*2
B^2+3B=70
B^2+3B-70=0
(B+10)(B-7)=0
B-7=0
B=7 ANS. FOR THE BASE.
H=7+3=10  ANS. FOR THE HEIGHT. 
PROOF:
35=7*10/2
35=70/2
35=35