Answer: The answer is (a) 3 × x = y and (b) x + x + x = y.
Step-by-step explanation: Let 'x' and 'y' denote the number of hours that Tina practised last month and this month respectively.
Then, according to the given information, we have
x = 15 and y = 45.
We can write the relation between 'x' and 'y' in two forms as follows -
(a) Multiplication form : 3 × 5 = 15 implies 3 × x = y.
(b) Addition form : 15 +15 +15 = 45 implies x + x + x = y.
Thus, the answers are (3 × x = y) and (x + x + x = y).