Step 2 and 3, for step 2, associative property should be commutative property, and step 3 should be associative property instead of the commutative property, i did all the work and its right, but how should i explain it?

Simplify the expression. -2/5(10+15m-20n)

Given: pqrs is a parallelogram prove: pr and qs bisect each other at t

Acaterer charges $500 plus $30 per guest to cater a wedding. walt and traci don't want to spend more than $8000 on catering. write and solve an inequality in terms of the number of guests, g, that can be invited. a) 30g ? 8000; g ? 267 b) 500g < 8000; g < 16 c) 500 + 30g < 8000; g < 250 d) 500 + 30g ? 8000; g ? 250