
Negative multiply negative = Positive
Negative multiply positive = negative

Thus the answer is -4a + 16b - 12c - 12d.
Answer:
113.04
Step-by-step explanation:
the equation for the area of a circle is pie times radius squared
60° because its not hafe evin and 90° is hafe so its 60°
Answer:
3x-4y=15
7x+y=4
Solve7x+y=4 for y:
7x+y=4
7x+y+−7x=4+−7x (Add -7x to both sides)
y=−7x+4
Step: Substitute −7x+4 for y in 3x−4y=15:
3x−4y=15
3x−4(−7x+4)=15
31x−16=15 (Simplify both sides of the equation)
31x−16+16=15+16 (Add 16 to both sides)
31x=31
(Divide both sides by 31)
x=1
Step: Substitute 1 for x in y=−7x+4:
y=−7x+4
y=(−7)(1)+4
y=−3(Simplify both sides of the equation)
Answer: x=1 and y=−3