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If~$\dfrac{3}{5}=\dfrac{M}{45}=\dfrac{60}{N}$ , what is $M+N$? （2008 AMC 8,7） 
Overseas Competition->Knowledge Point->Calculation Modules->Ratios and Proportions->Proportions->Simplifying Continued Ratios
Separate into two equations~$\dfrac{3}{5}=\dfrac{M}{45}$~and~$\dfrac{3}{5}=\dfrac{60}{N}$~and solve for the unknowns.~$M=27$~and $N=100$, therefore $M+N=\boxed{\left( E\right)127}.$. 