The mortality rate for children under 5 years of age around the world has been declining in a roughly linear fashion in recent years. The rate per 1000 live births was 93 in 1990 and 39 in 2018.

(a) Determine a linear equation that approximates the mortality rate in terms of time t, where t represents the number of years since 1900.

(b) One of the Sustainable Development Goals (SDG) of the World Health Organization is to reduce the mortality rate for children under 5 years of age to 25 by 2030. If this trend were to continue, in what year would this goal be reached?