Answer:
three times
Explanation:
Heat added is calculated according to the following equation
Q = mcΔT
where Q is the heat added
c is the specific heat capacity (of lead for the purposes of this question)
ΔT is the temperature change in Kelvin or degree Celsius
Q1 for heating lead = mc(373K-298K) = 75mc
Q2 for heating copper = m(3c)(373-298) = 225mc = 3(75mc) = 3Q1