can you help set up the equation?

Question

Three monkeys and two giraffes eat a combined 45 kg of food in a week. A single giraffe eats 2 kg less than twice what a monkey eats. How much does a single monkey eat?

Answer 1

The two equations are:

x= monkey eats

y= giraffe eats

3x + 2y = 45

y = 2x - 2; replacing this equation in the first, we obtain:

3x + 4x - 4 = 45

7x = 49

x=7 = Which is the number of kilograms eaten by a monkey in a week.

Answer 2

Hello again Cheryl.  Francisco set his two equations up correctly and after substituting y in the first equation correctly ended up with:

 

3x + 4x - 4 = 45

 

Unfortunately when Francisco solved for x he should have come up with:

 

7x = 49

 

which leads to x = 7

Answer 3

x=# kg a monkey eats

2x-2=# kg a giraffe eats

3x+2(2x-2)=45

3x+4x-4=45

7x-4=45

7x-4+4=45+4

7x=49

x=49/7

x=7 kg