ANSWER: 3d + 21
Explained:
To find the sun of d and 7 (thriced) we can use the equation
3(d+7)
Then distributing, we multiply 3 and D,
And then multiply 3 and 7
Then we are left with 3d and 21
Since these don’t have matching variables we can’t combine them, so the answer is 3d + 21
