so, they already used 4,885.78 this month, but whatever all five family members can use total for a month is 7,250.50, so since they already used 4,885.78, they have left 7,250.50 - 4,885.78 = 2364.72.

Answer:
x = -2 , y = 4
Step-by-step explanation:
given:
5x + 2y = -2 <em>*4</em>
4x + 3y = 4 <em>*5</em>
Solving simultaneously,
20x + 8y = -8 ....eq 1
(-) 20x +15y = 20 ...eq 2
.............................................
-7y = -28
y = -28 / -7
y = 4
using equation 2,
20x +15(4) = 20
20x = -40
x = -2
The most simplified version would be:
For number 15 and 16, you just have to find the absolute difference between the two points along the calibration of the protractor.
15. ∠BXC = |B - C| = |140° - 110°| = 30°
16. ∠BXE = |B - E| = |140° - 30°| = 110°
For numbers 20 and 21, apply the Angle Addition Postulate. This is when you add the individual interior angles to equate to the total angle.
20. ∠PQS = ∠PQR + ∠RQS
112° = 72°+ 10x°
x = 4
21. ∠KLM = ∠KLN + ∠NLM
135° = 47°+ 16y°
y = 5.5