to solve for the dimensions (x+7)(x+2)=66,
we can first use the foiling method to simplify the left side.
x^2 + 2x + 7x + 14 = 66
x^2 + 9x + 14 = 66
now, subtract 66 from both sides.
x^2 + 9x - 52 = 0
now, split this into two parentheses.
(x + 13)(x - 4)
since the root of -13 would give you negative values, x=4. This means that the dimensions of the rectangle are 11 and 6.
15(x+2000)=3300
15x + 30000 = 3300
subtract 30000 from both sides
15x = -26700
divide 15 from both sides so you get x alone
x =-1780
The number is 12
12 + 4 = 16
4 is a third of 12 and 12 + 4 = 16.