What is the answer to 7d+5=26, and 4t+1=25, 6r-3=15. Thanks! (missing letter)

Answer 1

I'll do the first one.

7d+5=26

7d + 5 - 5 = 26 - 5

7d = 21

d = 21/7

d = 3

I'll be glad to check your answers for the other two problems.

Answer 2

6r-3=15
???