15
12+9=21 21+15=36 36+13=49 49+6=55
by multiplying 15 and 12 twice then add up your answer and that's the perimeter
x - 12 = 3 Add '12' to both sides x = 3 + 12 x = 15
It is: (15-7)*(12-9) = 24
375
ext. 12-1=2+13=15
46. The pattern is add 3 then add 6 then add 9 then add 12 then add 15 ...
4-1=3 37+3=40 12+3=15 40 +15=55
Add up all the sides- 12+12+15+15. For the AREA, you would multiply length X width.
(8/12) + (2/10) = (10/15) + (3/15) = 13/15
51