pouvez-vous m'aider svp .... et expliquer comment vous avez fais...​

R=7/5 * -3/10 + (-4)
=-21/50 -4
=-21/50 - 200/50
=-221/50
S=-21/50 - (-3/10 * -4)
=-21/50 - 12/10
=-21/50 - 60/50
=-81/50
T= (7/4 - 3/10)(7/5 -4)
=(70/40 - 12/40)(7/5 -20/5)
=(58/40)(-13/5)
=-754/200
=-377/100