The 3rd angle that's not defined in the equation is supplementary to 115, so the angle is 180-115 = 65.
We can solve for the equation 65+(4k+5)+(6k+10)=180 -> 65+4k+5+6k+10=180 -> 10k+80 = 180 -> 10k = 100 -> k = 10.
To double-check(optional), we can plug k back into the equation, so 65 + 4*10 + 5 + 6*10 + 10 = 180 -> 100 + 65 + 5 + 10 = 180 -> 180 = 180, so we can confirm that k = 10.
Hi there! For this, we can simply divide 20.50 by 410 to find the tax rate. 20.50/410 is 0.05. That's in decimal form. Multiply by 100 to get the percent form. 0.05 * 100 is 5. That's the number in percent form. The sales tax rate is 5%.
