Answer:
u should put the question in English to so English people can also help
Perpendicular: the slope will be -6
Pass the point: Since we know slope is -6, then (-6)*(-3) + ? = 23 -> ? = 5
So answer: y = -6x + 5
5.250
To change a fraction to a decimal fraction divide the numerator by the denominator.
that is 21 ÷ 4 = 5.250 ( to 3 decimal places )