First, rewrite the expression as:
#-14/5(a^2/a)(b^3/b^10)#
Next, use these rules for exponents to simplify the #a# terms:
#a = a^color(blue)(1)# and #x^color(red)(a)/x^color(blue)(b) = x^(color(red)(a)-color(blue)(b))# and #a^color(red)(1) = a#
#-14/5(a^2/a)(b^3/b^10) =>#
#-14/5(a^color(red)(2)/a^color(blue)(1))(b^3/b^10) =>#
#-14/5(a^(color(red)(2)-color(blue)(1)))(b^3/b^10) =>#
#-14/5(a^(color(red)(1)))(b^3/b^10) =>#
#-14/5(a)(b^3/b^10) =>#
#-(14a)/5(b^3/b^10)#
Now, use this rule of exponents to simplify the #b# term:
#x^color(red)(a)/x^color(blue)(b) = 1/x^(color(blue)(b)-color(red)(a))#
#-(14a)/5(b^color(red)(3)/b^color(blue)(10)) =>#
#-(14a)/5(1/b^(color(blue)(10)-color(red)(3))) =>#
#-(14a)/5(1/b^7) =>#
#-(14a)/(5b^7)#