Question

The price of coffee has been reduced by 8% by how much percent must the new price be increased to retain the original price have?

Answer 1

(x+y+z)² = x²+y²+z²+2xy+2yz+2zx

(x+y+z)² = x²+y²+z²+2(XY+yz+zx)

(x+y+z)² = 40+2(30)

(x+y+z)² = 40+60 = 100

(x+y+z) = 10

Formula used,

(a+b+c)² = a²+b²+c²+2ab+2bc+2ca