If you distribute, then you get -10x+7.5
Note how -2.5 times 4x = -10x and how -2.5 times -3 = 7.5
The idea is that you multiply the outer term (-2.5) by each term inside
30 pounds after 10 weeks
9/3=3
3*10=30
300,000,000+60,000,000+2,000,000+31,000+1000+100
