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

Alexander hamilton and thomas jefferson were valuable cabinet members for president washington because
This protective covering on the axon is formed by a type of neurglia called schwann cells.
Was Teresa Avila executed in 1622?
How were Salem Village and Salem Town different?
The Mughal empire was replaced by the
The flag of a country contains an isosceles triangle.​ (Recall that an isosceles triangle contains two angles with the same​ measure.) If the measure of the thi
After independence ,most states adopted written Constitution that shared several features
what is descriptive words
After the last stop on Mr. Tuttle’s route, the number of students on the bus is 3/4 of its full capacity. Once Mr. Tuttle has completed picking up all the stude
in a controlled enviroment the varible that is change is called