Jack Deere made a deal with this father that he would mow the lawn for the entire summer. For the first mowing, he would charge a special introductory rate of $4, but for each mowing thereafter he would charge 85 cents more than the
previous rate. If Jack mowed the lawn a total of 21 times during the summer, how much did he earn in all?

if x decreases by 4 then y increases by 10

step-by-step explanation:

answer:   the paragraph proof is mentioned below.

step-by-step explanation:

given: in a δxwy where

such that, ∠wzx ≅ ∠yzx and zw≅zy

we have to prove that: segment zx is a perpendicular bisector of segment wy.

prove: since, zw≅zy ⇒ ∠wzy is a supplementary angle.

then, ∠wzy= 180°

⇒∠wzx + ∠yzx = 180° ( because xz divides ∠wzy into two parts)

but, ∠wzx ≅ ∠yzx ( given)

⇒∠wzy+∠wzy=180° ( by substitution)

⇒2∠wzy=180°

⇒∠wzy=90°

⇒∠wzy=∠yzx =90°

therefore, xz⊥wy where wz=zy

⇒zx is a perpendicular bisector of wy.

step-by-step explanation:

gym b charges $1.05 less per hour than gym a.

b.   e = 7.5h

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