The average of 4, 9, 16, 25 and x is 2x means that; (4+9+16+25+x)/5=2x Multiply both side by 5 5(54+x)/5=2x(5) 54+x=10x Subtract x to both side 54+x-x=10x-x 54=9x Divided 9 to both side 54/9=9x/9 x=6 Check: Substitute x with 6 (4+9+16+25+x)/5=2x (4+9+16+25+6)/5=2(6) 60/5=12 12=12; so x=6 which marks B as the correct answer. Have a nice day!
