7. The cost price of an article is Rs.1200 and the selling price is 5 times of its cost price. i. Find the selling price of the article? ii. Gain or Loss percent.

check the picture below.

well, the angle at the vertex d is clearly not a right-angle, let's check for the one at the vertex f which does look like,   however if it's indeed, that means ef is perpendicular to df, in which case their slopes will be negative reciprocal of each other.

so the negative reciprocal of the slope of ef is 1, however the slope of df is not 1, is 1/2, so nope, they're not perpendicular lines.

a c

step-by-step explanation:

what shape is

15.36 per mile

but forgot to round

i am pretty sure