a) $3(x+y)=$
\(\boxed{3(x+y) = 3x + 3y}\)
Step 1 :We need to find the expression for 3 times the sum of x and y.
Step 2 :expr = 3*x + 3*y
Step 3 :\(\boxed{3(x+y) = 3x + 3y}\)