Evaluate: (5xy)² if x = 4 and y = 2

Evaluate:-4x if x = 3

Simplify: 20x/5 if x=10

Simplify: (5xy) (-4) if x=1 and y=2

Evaluate: x⁴ ÷ x² if x = 2

Evaluate: x ^ -1 if x = 5

Simplify: 15y/3 if y=7

Evaluate: 10x-4x+4y+5y if x=-1 and y=1

Evaluate: $2x+2y$ if $x=2$ and $y=2$

Evaluate: (- 5x)⁰ if x = 100