In below formula for arithmetic sequence you can fill in a=7 (start), d=2 (interval) and n=35 (nr terms) and you get
17.5(14 + 34*2) = 1435
Confirmed by a brute-force addition: 7+9+11+13+15+17+19+21+23+25+27+29+31+33+35+37+39+41+43+45+47+49+51+53+55+57+59+61+63+65+67+69+71+73+75=1435
So I would round it to 340 and 40 because if the number is lower than 5 than take it DOWN to the nearest ten if it's five or above take UP to the nearest ten
Hope it helped you
solve for y
2x−4y=10
-2x -2x subtract -2x from both sides
-4y = -2x +10
-4 -4 Divide both sides by -4 (coefficient on y)
y = -2/-4x + 10/-4
y = 1/2x - 5/2
the slope is the number on the x (coefficient)
and its 1/2
12/100x10000 = 1200
17/100x8000= 1360
1360+1200 = 2560
18000 - 2560 = $15,440 (final cost)