6. Write a PHP program that calculates and prints both the arithmetic mean and the harmonic mean of the two integers x and y, where x=12 and y=13. Arithmetic mean =2x+y Harmonic mean =1/x+1/y2 7. Given that $a=6,$b=7,$c=2, and $d=5, figure out the value of $x for the following expressions (do not write a program): 1) $x=$a5.0; 2) $x=$d/$c+6; 3) $x=$a+$b/($c$d); 4) $x=$a+$b/$c$d 5) $x=($a+$b)/$c$d 6) $x=($a/($c$d)+$b)($c$d); 7) $x=($a/$c$d+$b)$c$d 8) $x=$b%$d$c+$a