Here's the solution,
The given triangle is an <u>equilateral triangle</u>, because it's all angles measure 60° each
now,
Area of an equilateral triangle :
=》

where,
=》

=》

=》

or
=》

He must get a 65 as a minimum grade on his third test to get an average of 70.
Equation is
85 + 60 + x
------------------- greater than or equal to 70
3
3/47 is a rational number
p/q is a rational number, where p and q are real integers, and q does not equal to 0.
Sorry, I wish I could help, but I haven't learned this yet
;-;