First, rewrite this expression as:
#(7/7)(p/p^7)(q^9/q)(r/r)(s/s^3) =>#
#1(p/p^7)(q^9/q)1(s/s^3) =>#
#(p/p^7)(q^9/q)(s/s^3)#
Next, use these rules of exponents to simplify the #q# term:
#a = a^color(blue)(1)# and #x^color(red)(a)/x^color(blue)(b) = x^(color(red)(a)-color(blue)(b))#
#(p/p^7)(q^9/q)(s/s^3) => (p/p^7)(q^color(red)(9)/q^color(blue)(1))(s/s^3) =>#
#(p/p^7)(q^(color(red)(9)-color(blue)(1)))(s/s^3) => (p/p^7)q^8(s/s^3)#
Now, use these rules of exponents to simplify the #p# and #s# terms:
#a = a^color(red)(1)# and #x^color(red)(a)/x^color(blue)(b) = 1/x^(color(blue)(b)-color(red)(a))#
#(p/p^7)q^8(s/s^3) => (p^color(red)(1)/p^color(blue)(7))q^8(s^color(red)(1)/s^color(blue)(3)) =>#
#(1/p^(color(blue)(7)-color(red)(1)))q^8(1/s^(color(blue)(3)-color(red)(1))) => (1/p^6)q^8(1/s^2) =>#
#q^8/(p^6s^2)#
