4x+(x+5)=20
5x+5=20
5x=15
X=3
Easy,
finding the complement (net price) subtract the discount percentage by 100% to get the net price percentage. Net price equals the list price minus the discount price.
100%-35%=65%
Multiply the list price ($1,400) by the complement.
Net price= 0.65(1,400)=$910
Thus, the new price is, $910.
L: 1750, M:1750-480=1270
Lisa gave some stamps to Mark so Lisa now has 1750-x and Mark has 1270+x. Mark also has 3 times as many as Lisa now: (1750-x)*3=1270+x
5250-3*x=1270+x
4*x=3980, x=3980/4, x=995
So Lisa gave 995 stamps to Mark.
At first Mark had 1270 stamps. Lisa now has 1750-995=755 stamps.
The answer is the last one (15+6)+3