Sha7contubstewood
Sha7contubstewood Sha7contubstewood
  • 03-02-2016
  • Mathematics
contestada

John is twice as old as Mary. The sum of their ages is 21. How old is Mary?
Let J = John's age and M = Mary's age.

Respuesta :

apologiabiology
apologiabiology apologiabiology
  • 03-02-2016
j=john
m=mary
j is 2 times as old as mary
j=2 times m

sum is 21
m+j=21
find mary
subsitute

j=2m therefor subsitute 2m for j
m+2m=21
add like terms
3m=21
divide by 3
m=7

mary=7
Answer Link

Otras preguntas

An artist of the mid-1800s who portrayed the harsh lives of slum dwellers was probably using what artistic style?
Will mark brainliest if the correct answer is given △ABC is similar to △QRS . Also, side AB measures 50 cm, side AC measures 60 cm, and side QS measures 6 cm.
what is the main reason equatorial ocean water is warmer than polar ocean water?
Geometry question slope intercept form WILL GIVE 20 POINTS AND BRAINILEST IF ANSWERED CORRECTLY Write an equation in slope-intercept form for each line describe
Cell b10 contains a date, such as 9/1/2014. which formula determines how many days have passed between that date and the current date?
Geometry Two sides of a triangle have lengths 11 and 18. Write an inequality to represend the possible lengths for the third side, x.
help me with this question
The island chain of hawaii was formed by a mantle hot spot. the island of maui is 1.1 million years old while the big island of hawaii is 0.4 million years old.
Need help with these asap
Henry Clay planned to fund the American System largely through what