Answer:
26
Step-by-step explanation:
5x+6y
substitute x=16 and y=-9:
5*16+6*(-9)
=80-54
=26
easy
x=5 and 3
x^2-8x+21=6
x^2-8x+21+16=6+16
(x-4)^2=1
(x-4)=±1, x=5 and 3
