解答

それでは私も解いてみます！

 ※ 拡大可能

M1[Nm] + M2[Nm] – M3[Nm] = 0

(r1[m] × F1[N]) + (r2[m] × F2[N]) – (r3[m] × F3[N]) = 0

｛(1[m] + 1[m]) × F[N])｝ +｛1[m] × (1[kg] × 10[m/s²])｝ -｛2[m] × (3[kg] × 10[m/s²])｝ = 0

(2[m] × F[N]) + (1[m] × 10[N]) – (2[m] × 30[N]) = 0

2F[Nm] + 10[Nm] – 60[Nm] = 0

2F[Nm] – 50[Nm] = 0

2F[Nm] = 50[Nm]

F[N] = 25[N]　← 答え！！

皆さん合っていたでしょうか？