I need help please

Question

Leila, Sam, and Boris sent a total of 115 text messages during the weekend. Leila sent 10 fewer messages than Boris. Sam sent 3 times as many messages as Boris. How many messages did they each send?

Answer 1

Write equations for what you're given, then look at them to see what you have to work with.

Leila, Sam, and Boris sent a total of 115 text messages

L+S+B = 115

Leila sent 10 fewer messages than Boris.

L = B-10

Sam sent 3 times as many messages as Boris.

S = 3B

 

Aha!  This will be pretty simple.

The second and third equations are expressions for L and S in terms of B.

Use those expressions to substitute for L and S in the first equation.

L+S+B = 115

(B-10)+ 3B + B = 115

5B -10 = 115

5B = 125

B = 25

Now you can use the second and third equations to find L and S.

L = B-10 = 15

S = 3B = 75

 

Check:

25+15+75 = 115

115 = 115