Together, Sarah's two cats have the same mass as her dog, 11 kg. The mass of one cat is

1500 g greater than the mass of the other. What are the masses of the two cats?

First, lets do all calculations in kg. 1kg=1000 grams

Lets set 1 cat's mass as x.

Lets set the other cat's mass as y.

1) x+y=11

2) y=x+1.5

Lets plug eq 2 into eq 1.

x+x+1.5=11

2x+1.5=11

2x=9.5

x=4.75 kg

If one cat weighs 4.75 kg, then the other must weigh 6.25 kg.

So cat1=x

cat2=y

x+y=11kg

11kg=11000g

x=y+1500

subsitute

y+1500+y=11000

subtract 1500

2y=9500

divide by 2

y=4750

subsitue

x=4750+1500

x=6250

one cat weighs 6250g and the other weighs 4750g