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

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

Why did the pilgrims celebrate the first thanksgiving?

Which action is most important when two people are “finding ground” during conflict resolution? A. Identify important facts and issues on which both people can

UMMM who's good at science?!?!?!What causes the convection cell to turn up at point A?

How do you solve (a^3b)^4(ab^6)^2?

What is the prime factorization of 88 and 50. please have them separate.

Why would you use the associative property of multiplication to sole (10*4)*2 how would you regroup the factors?

34. The following question refers to “Narrator and Voice”: The attitude a speaker or writer takes toward a subject, character, or audience is called the narrato

Paula spent 3/8 of her allowance on clothes and 1/6 on entertainment what fraction of her allowance did she spend on other items

The _____ of a position-time graph represents an object’s velocity. (I don't have answer choices)

what does the uses of words such as justice and tranquility in the preamble show A.Metaphor B. Jargon C.diction D.slang