Since it's a right triangle you can use the Pythagorean theorem or Trig (Soh Cah Toa).
I'll just use the Pythagorean theorem : a² + b² = c²
a = 9
b = x
c = 18
9² + x² = 18²
81 + x² = 324
x² = 324 - 81
x² = 243
x = √(243)
factor 243 to find a perfect square
x = √(3*81)
x = 9√(3)<u />
Answer:
9
Step-by-step explanation:
Let's first convert this to numbers. When a number is decreased by a certain amount, that is the same as saying that something is subtracted from it. Therefore:
a-7=2
Add 7 to both sides:
a-7+7=2+7
a=9
Hope this helps!