Answer:
63
Step-by-step explanation:
Set up the proportion
(6x+3)/17 = (8x - 1)/21 Cross Multiply
21 * (6x + 3) = 17 (8x - 1) Remove the brackets
126x + 63 = 136x - 17 Subtract 126x from both sides
63 = 136x - 126x - 17 Combine
63 = 10x - 17 Add 17 to both sides
63 + 17 = 10x Combine the left
80 = 10 x Divide by 10
80/10 = x
x = 8
Now you want 8x - 1
8*8 - 1 = 63
