A straight line is 180°. So you can do:
(15x - 4) + (5x - 8) = 180 Simplify
20x - 12 = 180
20x = 192 Find the value of x
x = 9.6
m∠ABD = 15x - 4 Plug in x = 9.6
m∠ABD = 15(9.6) - 4 = 144 - 4 = 140°
m∠DBC = 5x - 8 Plug in 9.6
m∠DBC = 5(9.6) - 8 = 48 - 8 = 40°
D, its (x,y) and (8.2,5.7) are the only ones that match up
Kim's Loan:
Let A = amount borrowed from bank A.
Let B = amount borrowed from bank B.
The total loan is $55,000.
Therefore
A + B = 55000 (1)
Bank A charges 8% interest. The interest after 1 year is 0.08A.
Bank B charges 11% interest. The interest after 1 year is 0.11B.
Total interest after 1 year is $5,000.
Therefore
0.08A + 0.11B = 5000 (2)
From (1), obtain
B = 55000 - A (3)
Substitute (3) into (2).
0.08A + 0.11(55000 - A) = 5000
0.08A + 6050 - 0.11A = 5000
-0.03A = -1050
A = -1050/-0.03 = 35000
Answer: Kim borrowed $35,000 from bank A.
Jack's Loan.
A = loan from bank A.
B = loan from bank B.
The total loan is $10,000.
Therefore
A + B = 10000 (4)
Bank A charges 5% interest and bank B charges 6% interest.
Total interest after 1 year is $530, therefore
0.05A + 0.06B = 530 (5)
From (4), obtain
B = 10000 - A (6)
Substitute (6) into (5).
0.05A + 0.06(10000 - A) = 530
0.05A + 600 - 0.06A = 530
-0.01A = -70
A = -70/-0.01 = 7000
Answer: Jack borrowed $7,000 from bank A.
Simplified: 3x+7y+(-2y)+9
Coefficient of y: 5
Constant: 3 and 6
