Here we are finding x, given the angle and adjacent side. To find x we will use the function cos as cos = a/h.
So let's do cos(35°) = 15cm / x
cos(35°) = 0.8 (1 dp)
x = 15 cm / cos(35°)
x = 18.3 cm (1 dp)
Original price is $150 so you times 150 by 0.40
150 x 0.40 = 60
So you take the $150 and you subtract $60 from $150
150 - 60 = 90
So the answer is $90
1 triangle: 2*6 + 1*5
2 triangles: 2*6 + 2*5
3 triangles: 2*6 + 3*5
So for n triangles: p = 2*6 + n*5 = 12 + 5n
The answer is below what the dude said