First, expand the term in parenthesis by multiplying each term within the parenthesis by the term outside the parenthesis:
#0.5t + color(red)(0.25)(t + 16) = 4 + 0.15t#
#0.5t + (color(red)(0.25) * t) + (color(red)(0.25) * 16) = 4 + 0.15t#
#0.5t + 0.25t + 4 = 4 + 0.15t#
#(0.5 + 0.25)t + 4 = 4 + 0.15t#
#0.75t + 4 = 4 + 0.15t#
Next, subtract #color(red)(4)# and #color(blue)(0.15t)# from each side of the equation to isolate the #t# term while keeping the equation balanced:
#0.75t + 4 - color(red)(4) - color(blue)(0.15t) = 4 + 0.15t - color(red)(4) - color(blue)(0.15t)#
#0.75t - color(blue)(0.15t) + 4 - color(red)(4) = 4 - color(red)(4) + 0.15t - color(blue)(0.15t)#
#(0.75 - color(blue)(0.15))t + 0 = 0 + 0#
#0.6t = 0#
Now, divide each side of the equation by #color(red)(0.6)# to solve for #t# while keeping the equation balanced:
#(0.6t)/color(red)(0.6) = 0/color(red)(0.6)#
#(color(red)(cancel(color(black)(0.6)))t)/cancel(color(red)(0.6)) = 0#
#t = 0#