How can Makena use the expression for a$,$

a $=$

m$2$ m$1$m$1+$ m$2$

g

$,$ and Newton's second law to find the tension in the cord?

Substitute a into Newton's second law equation for either mass, and solve for m$.$Solve

a $=$

m$2$ m$1$m$1+$ m$2$

g

for g$.$It is not possible to find the tension in the cord, even given Newton's second law and an expression for a$.$Substitute a into Newton's second law equation for either mass, and solve for T$.$