From A to B
#color(white)("XXX")#time #= 1/2# hr.
#color(white)("XXX")#ave. speed #=(0+38)/2# mph #=19# mph
#color(white)("XXX")#distance #=1/2# hr #xx 19# mph #= 9 1/2# miles.
From B to C
#color(white)("XXX")#time #= 1/2# hr.
#color(white)("XXX")#ave. speed #=(38+40)/2# mph #=39# mph
#color(white)("XXX")#distance #=1/2# hr #xx 39# mph #= 19 1/2# miles.
From C to D
#color(white)("XXX")#time #= 1/4# hr.
#color(white)("XXX")#ave. speed #=(40+70)/2# mph #=55# mph
#color(white)("XXX")#distance #=1/4# hr #xx 55# mph #= 13 3/4# miles.
From D to E
#color(white)("XXX")#time #= 3 3/4# hr. #= 15/4# hr.
#color(white)("XXX")#ave. speed #=(70+70)/2# mph #=70# mph
#color(white)("XXX")#distance #=15/4# hr #xx 70# mph #= 262 1/2# miles.
From E to F
#color(white)("XXX")#time #= 1# hr.
#color(white)("XXX")#ave. speed #=(70+0)/2# mph #=35# mph
#color(white)("XXX")#distance #=1# hr #xx 35# mph #= 35# miles.
Total Distance to San Diego
#color(white)("XXX")9 1/2 + 19 1/2+ 13 3/4 + 262 1/2+35# miles
#color(white)("XXX")=340 1/4# miles
