Question 233810
A=BH/2 TRIANGLE AREA FORMULA.
B=2H+2 SUBSTITUTE (2H+2) FOR B IN THE AREA FORMULA & SOLVE FOR H.
30=(2H+2)H/2
30=(2H^2+2H)/2 CROSS MULTIPLY.
2H^2+2H=60
2H^2+2H-60=0 DIVIDE ALL TERMS BY 2.
2(H^2+H-30)=0 
2(H+6)(H-5)=0
H-5=0
H=5 ANS. FOR THE HEIGHT.
B=2*5+2=10+2=12 ANS. FOR THE BASE.
PROOF:
30=5*12/2
30=60/2
30=30