4. Write a PHP program that calculates and prints the area and perimeter of a rectangle whose width is 4cm and its height is 6cm. Hint: area = width height perimeter =2( width + height ) 5. Write a PHP program that prints the diameter, area and circumference of a circle of a radius of 5.25cm. Use the constant value 3.14 for pi (). Hint: diameter =2r area =r2 circumference =2r 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=Sa5.0 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%$dSc+$a