Velocity time graph and determining the time taken

Question

The velocity of a particle and time are as follows $40ms^-1 in 1 sec$, $30ms^-1 in 2 sec$, $20ms^-1 in 3 sec$, $10ms^-1 in 4 sec$. How to calculate the time taken to trave $35m$ for the velocity-time graph. I plotted the graph which was negative acceleration graph. I know the distance was the area under the curve. But I am bit confused to get an are of $35ms^-2$.

Answer 1

The particle travels $40*1+30*2+20*3+10*4$ m in a total of 10 seconds.

or, 200 m in 10 secs.

then, 35 m in 350/200 secs Or, 1.75 secs.