This is a systems of equations.
s = stamp, e = envelope
Substitute e + 9 for s.
.1(e + 9) + .13e = 2.51
Simplify.
.1e + .9 + .13e = 2.51
Simplify.
.14e + .9 = 2.51
Subtract .9 from both sides.
.14e = 1.61
Divide both sides by .14.
e = 11.5
Now, you can input e into the other equation.
11.5 + 9 = s
Simplify.
20.5 = s
s = 20.5, e = 11.5
9514 1404 393
Answer:
C. 837
Step-by-step explanation:
The remaining angle is ...
C = 180° -A -B = 180°-62° -67° = 51°
The law of sines tells us that the length AC is ...
AC/sin(B) = AB/sin(C)
AC = AB·sin(B)/sin(C) = 40·sin(67°)/sin(51°)
Using the area formula given, we now have ...
area = 1/2(AB)(AC)sin(A)
= (1/2)(40)(40·sin(67°)sin(62°)/sin(51°) ≈ 836.7
The area of the triangle is about 837 square units.
