Answer:
Step-by-step explanation:
he has 1/4 remaining as he has only used 3/4
Distribute 3
6t+15=5t+25
subtract 5t from 6t
t+15=25
subtract 15 from both sides
t=10
11*57+X(1+2+3+.....+56)
=11*57+X(1+56)*56/2
=627+1596X
=19779
X=(19779-627)/1596=12
Your answer is C