There is work done by three different forces
(a) work of the force "F"
"W_F=F\\cdot s\\cdot \\cos35\u00b0=400\\cdot (0.2+0.6)\\cdot\\cos35\u00b0=262J"
(b) work of the block weight
"W_W=mg\\Delta h=mg\\cdot0.8\\cdot \\sin40\u00b0=8\\cdot 9.8\\cdot0.8\\cdot \\sin40\u00b0=40J"
(c) work of the spring force
"W_S=-\\frac{k}{2}(0.6^2-0.2^2)=-\\frac{300}{2}(0.36-0.04)=-48J"
So, total work
"W_t=262+40-48=254J"
Answer. "(b) 254 J"
Comments
Dear eve, 0.2+0.6=0.8 m
How did you come up with the value 0.8?
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