We have to use the area formula for triangles
[tex]A=\frac{bh}{2}[/tex]Where A = 60 cm2, and h = 10 cm, let's replace these values and solve for b
[tex]\begin{gathered} 60=\frac{10b}{2} \\ 60=5b \\ b=\frac{60}{5} \\ b=12\operatorname{cm} \end{gathered}[/tex]