Constant of proportionality is 4
equation: x/y = 4
explanation:
let's take 20 and 5 for example, if you divide 20 by 5, you will 4 of course. that's the proportionality for the first one. if you continue to divide x value by y value you will get 4. for the last two you would divide 28 by 4 and multiply 8 by 4.
3(a + b) and 3a + b - NOT EQUIVALENT because
3(a + b) = 3a + 3b
<em>used distributive property a(b + c) = ab + ac</em>
4(x + 2y) and 8y + 4x - EQUIVALENT because
4(x + 2y) = (4)(x) + (4)(2y) = 4x + 8y = 8y + 4x
<em>used distributive property a(b + c) = ab + ac</em>
<em>and commutative property a + b = b + a</em>