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RV-05-001 · Area equality with algebraic side lengths

x8x + 515
Diagram not accurately drawn

Rectangle A has sides x cm and 8 cm. Rectangle B has sides (x + 5) cm and 15 cm. The area of B is 131 cm² greater than the area of A. Find x and the perimeter of B. Show your working.

Forming & Solving Linear Equations from Area Equality Booklet p. 2 & p. 10
Method
1) Form equation: Area B − Area A = difference
2) Expand bracket and collect x terms
3) Kill, kill to solve for x, then substitute into Perimeter B
Worked Example (RV-05-001)
Booklet p. 10 — Form linear equation, collect like terms, and "Kill, kill" to solve for xx:
1) 15(x+5)−8x=13115(x+5)-8x=131
2) 7x=567x=56
3) x = 8.
4) Perimeter = 2(15 + 13).
5) 56 cm.
x = 8; perimeter = 56 cm.