Answer:
a=4
Step-by-step explanation:
if a+5=2a+1
then 5-1 = 2a-a
so 4 = a
The 11th triangular number = 66
.636 o\would be the answer
Answer:
For the first one the answer is 60 idk about the 2 one tho
Step-by-step explanation:
Answer:
53
Step-by-step explanation:
i had to use this old method (pic related).