X = pencils, y = pens
8x + 6y = 8.50
4x + 4y = 5.....multiply by -2
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8x + 6y = 8.50
-8x - 8y = -10 (result of multiplying by -2)
-----------------add
-2y = - 1.50
y = -1.50 / -2
y = 0.75 <=== pens cost 0.75
4x + 4y = 5
4x + 4(0.75) = 5
4x + 3 = 5
4x = 5 - 3
4x = 2
x = 2/4
x = 0.50 <== pencils cost 0.50
Its typical because 60 between 100. 8 times 10 seconds equals 80 which is in between so Noah's heart rate is typical.
5x20=100 100+200=300 or atlas what i think if this is wrong i am sry but if isn't I'm glad I'm able to help ^u^
Ok so substitute the values. a=3 b=2 and c=-3
-3^(2)-3(2)^(3)+(-3)^(2)+2(2)^(3)-(-3)^(2)=-9-24+9+16-9=-33+25-9=-42+25=-17
