Divide the number of people by the number of plates per pack:
138 / 12 = 11.5
He need to buy 12 packs of plates to have enough.
X = 2y + 7 ...............(1)
2x + 2y = 200 ........(2)
Substituting the expression for x in equation (1) into equation (2) gives
2(2y + 7) + 2y = 200 .....(3)
Equation (3) simplifies to
6y = 186
Therefore y = 31 feet.
Substituting the value for y into (1) gives
x = 69 feet.
The expression 8(-3) represents the recession of the coastline after 8 years if the coastline recedes 3 centimeters each year. 8(-3)=-24. So, the coastline's new position is 24 centimeters farther inland than it was 8 years ago.
answer= 24