Please solve

Question

2. Each of the following refers to three quantities. Introduce variables to represent the first two of these quantities, and then represent the third quantity in terms of the variables used for the first two.

 

Sue’s age; Mary’s age; the sum of Sue’s and Mary’s ages
Sue’s age; Mary’s age the difference between their ages five years from now. (Sue is older than Mary)
Sue’s age; Mary’s age half of Sue’s age two years ago
The number of minutes it takes Alphonse to do the job; how much-what portion-of the job they can do in one minute if they work together.

Answer 1

Karen:

 

Sue's age s, Mary's age m. 

 

Line 1. s + m = T, say.  Then m = T - s.

 

Line 2: Five yrs from now, Sue will be s+5, Mary will be m+5, which is T - s + 5. Given (s+5) - (T-s+5) = D say.

 

Line 3: Two years ago Sue's age was s - 2. Mary's was m-2 = T-s-2.  Given (s-2) = 2(T-s-2)

 

Line 2 gives 2s = D+T, s = (D+T)/2

 

Line 3 gives 3s = 2T - 2. s = 2(T-1)/3.

 

You can tackle Alphonse's problem.  I can not understand what is said in the question.  (Who are "they"?)

 

Dr, G,