This is my third time posting this question, which is my fault. my teacher does not want me to use substitution rules.

using rules of inference and no substitution, prove that:

–p +-q) + (pλq)

and:

(5l + d) + (byd)

multiply length by height. multiply the length by the height, and then double the product. work out 10 x 10 results = 100 square inches, then work out 100 x 2 = 200. the answer is 200 square inches.

step-by-step explanation:

the height of the surface increases from the center out to the sides of the road.

step-by-step explanation:

as we move out we move away from the x-axis.

and as mentioned in the problem statement that height of a road increases when we move away from the center x.

hence proved that 3rd option

the height of the surface increases from the center out to the sides of the road.

is the correct option.

answer: $1794

step-by-step explanation: