Primary 6 - Algebra

John has 80 sweets and Alan has x sweets
fewer than John. 
​
​(a) How many sweets must John give to Alan so that both of them will have an equal number of sweets?
​      Express your answer in x.
(b) If x = 40, how many sweets do they have altogether?

Mark, Aaron and Jack received marbles in the ratio of 6:5:3.
If Mark received 18y marbles,
(a) find the number of marbles Aaron received in terms of y.
(b) find the total number of marbles the three children had in terms of y.

At fast food restaurant, a cup of sundae costs $r. A chicken burger costs 3 times as much as the sundae. A box of fries costs $3. 

(a) Find the total cost of a sundae and a chicken burger. Express your answer in terms of r.
​
(b) If r=2, how much do 3 chicken burgers and 2 boxes of fries cost?

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